Traffic Light behavior not as expected

(Using dT 6.2.1) I must be missing something... I've got a couple of traffic light graphs in a dashboard that are not displaying the way I think they should. Here's the setup:

Measure - Memory Utilization

Dashlet specific time period - Last 15 minutes

Thresholds - Upper warning = 75% Upper Severe = 90%

Aggregation = Average

So in this screenshot it shows that the average for the last 15 minutes was 57%. Why then is it showing a Severe Icon? I would expect to see a green light. To me, it seems like rather than showing the average of the last 15 minutes, the light is showing the maximum of the last 15 minutes.

1 Reply

The Traffic Light chart is considered a "historical" chart, meaning it's evaluating worst-case the aggregation on a trending basis for the full timeframe configured. To evaluate (approximate, really) the full timeframe, reduce the resolution from 10s to 5 or 15 minutes for that chart, using the second icon in the upper right when you hover.

Aternatively, you can define much more nuanced rules by defining an Incident for the measure and then using an Incident chart as your visualization for a traffic light. This can help you tune sensitivity and differentiate between the current and historical state of any metric you want to evaluate. More info:

I'm not sure I follow... The "timeframe" for the traffic light chart on my dashboard right now is set to 15 minutes. It seems that you're right though, that it is ignoring the average for the last 15 minutes, and just showing the worst-case. Which doesn't make any sense to me. If I wanted worse-case I'd choose the "maximum" aggregation, right?

The timeframe is not the issue, the resolution is. It is evaluating all datapoints separately on the line chart version against your threshold. If you want the average of the last 15 minutes you need to reduce the resolution as I described above, so it shows just one data point.

AH HA!!! Thank you! That fixed it. I was confusing timeframe and resolution. So if I understand correctly... Timeframe is the total collection of datapoints to use, and resolution determines how many datapoints are evaluated at once? So I may have had 15 minutes worth of data, but I was evaluating in 10 second chunks. Now I've set the evaluation for 15 minutes.